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Bioaccumulation: A Slow Death

What is bioaccumulation?

Bioaccumulation refers to the accumulation of substances in living organisms. Many organisms may be exposed to toxic substances that find their way into sediment or aqueous environments. Depending on the bioaccumulation potential of these toxic chemicals, they may build up in organisms’ tissues and internal structures. This process presents serious threats to the health of numerous ecosystems, as bioaccumulation often increases with each trophic level. Many products undergo toxicology testing and biodegradation studies, but if they are not subjected to bioaccumulation studies, the true extent of their environmental impact is unknown. Many industrial chemicals and consumer products inadvertently find their way into aquatic and sediment ecosystems regardless of their intended disposal, leading to unintended bioaccumulation in various organisms.

Bioaccumulation is a big factor in environmental pollution and has only been acknowledged recently. The most recent news on bioaccumulation suggests that its effects are more far-reaching than originally thought. There is evidence of bioaccumulation from the deepest ocean trenches to our own backyards. Pope Francis even addressed his concerns on bioaccumulation in the Encyclical Letter Laudato Si’ of The Holy Father Francis on Care for Our Common Home published in May of 2015. He states, “Industrial waste and chemical products utilized in cities and agricultural areas can lead to bioaccumulation in the organisms of the local population, even when levels of toxins in those places are low. Frequently no measures are taken until after people’s health has been irreversibly affected.”

What causes bioaccumulation?

Any substance with low biodegradation potential that is released into the environment has the potential to bioaccumulate. Perhaps the most concerning substances are the persistent organic pollutants (POPs) that exhibit endocrine-disrupting properties in organisms. POPs are inherently lipophilic, meaning these compounds readily bioaccumulate in organisms, and increase cumulatively at each trophic level. POPs are often released into the environment through industrial accidents and discharges, landfill leakage, or incomplete incineration. These substances do not naturally degrade so they may persist in the environment potentially indefinitely. They can spread great distances, including to seemingly isolated environments, such as polar regions and the open ocean. Two main POPs are polybrominated diphenyl ethers (PBDEs, used as flame retardants), and polychlorinated biphenyls (PCBs, used as dielectric fluid). From the time PCB production began in the 1930s to when production was ceased in the 1970s, the total production worldwide was around 1.3 million tons.

Who is affected by it?

An estimated 35% of the total PCB product from the 20th century is now thought to be residing in coastal sediments and open oceans. POPs have recently been found in organisms in some of the deepest ocean trenches. Ocean trenches are thought to be pristine environments, but scientists are discovering that their locations and topography may actually make them sinks for contaminants and litter that are discarded into the sea. A group of researchers measured levels of POPs in crustaceans residing in the Mariana Trench and the Kermadec. PCB and PBDE were found in all samples of all species at all depths in both trenches. In fact, the POP levels were so high that they surpassed similar samples taken at the most polluted rivers and bays in Asia. The scientists conclude, “Even the deepest chasms of the ocean are no longer pristine. The challenge moving forward is to determine the physiological consequences of such contamination and understand knock-on effects on ecosystem function.”

Closer to home, in an Environmental Science & Technology article from March 2017, scientists reported that Californian women were found to have trace amounts of Polybrominated Diphenyl Ethers (PBDEs) in their bloodstreams. PBDEs, commonly used as flame retardants, were banned in 2005, but their persistent bioaccumulation enabled the existing amounts of them in the environment to continue to affect humans over ten years later. Studies in the past focusing mostly on young women, suggested that PBDE levels in people dropped right after the chemicals were banned in 2005. These more recent studies on older women show, however, that PBDE levels are either plateauing or increasing. When PBDEs were still in production, they could be found primarily in furniture and other household sources. “As the ban took effect and these products have been replaced with newer PBDE-free products, exposures from indoor dust probably have declined. However, as the old products are now being disposed of in landfills and incinerators, it is likely that the outdoor environment is becoming increasingly contaminated,” says lead author of the study, Susan Hurley. She thinks that as an increasing number of studies like hers are performed, it will “underscore the urgency to take additional
regulatory actions to manage the safe disposal of PBDE-laden furniture and other PBDE-laced products to reduce environmental contamination and minimize dietary exposures.”

What can we do to prevent it?

Everyone, from the deepest ocean fauna to homo sapiens, is affected by bioaccumulation. The ramifications of it are astounding. Environmental fate, ecotoxicity, and bioaccumulation testing on all chemical products is the best way to prevent further damage to our ecosystems.

The Environmental Protection Agency’s (EPA) Toxic Substances Control Act (TSCA) monitors bioaccumulation properties in chemicals used in industrial and consumer products to determine whether chemicals are associated with or responsible for adverse effects on the environment. EPA programs like Safer Choice offer manufacturers a way to certify that their products are more environmentally friendly. Programs like these require a product to undergo a series of ecotoxicological and environmental fate tests, including bioaccumulation testing.

Situ Biosciences offers several bioaccumulation methods for fish and oligochaetes. Our toxicology tests include methods for fish, aquatic invertebrates, and aquatic plants. We also provide analytical and environmental fate testing to ensure that the properties of your product are known.